Apparatus for electromagnetostrictive transmission and reception



Sept 17, 1935. G. w. PIERCE- APPARATUs FOR ELEcTRomGNETosTRIcTIvE Tm'msnu-ssln'V AND vRExmPTIoH original Filed-Nov. 19. lead Patented Sept., i7, 1935 sTATEs PATENToFFIcl-z APPARATUS FOR ELECTROMAGNETOSTRIC- TIVE TRANSMISSION AND RECEPTION George Washington Pierce, Cambridge, Mass.

18 Claims. (Cl. 177-386) The present invention relates to the transmission and reception of intelligence, using sound as the agency of communication, and more particularly to communication by sound through air,

water, or other dense media, The present application is a division of application Serial No. 496,809, filed November 19, 1930, and a continuation in part of application, Serial No. 158,452, filed January 3, 1927, which matured, on March 11, 1930, into LettersPatentNo. 1,750,124.

A feature of the invention is the use of tuned magnetostrictive vibrators. Magnetostrictive vibrators are constituted.- of a xnagnetostrictiveV core disposed in an electromagnetic field, such as maybe produced by a coil or winding in an electric circuit.

The invention will be explained in greater detail in connection with the accompanying drawing, in which Fig. 1 is a diagrammatic view, partly in section, of apparatus and circuits constructed and arranged to illustrate a principle of the present invention, the section being taken 5 upon the line 4I-I of Fig. 2, looking in the direction of the-arrows; Fig. 2 is an elevation of the same; and Fig. 3 is a diagrammatic view of a transmitting-and-receiving system according to the present invention, it being understood that. either end of the system may be operated either to transmit-or to receive.

A plurality of rigid cores 2 of highly magnetostrictive material, are shown in Fig. 1, disposed side by side and spaced from each other, and each axially positioned in, and driven by, an inductive and resistive, energizing, field solenoid coil 22. 'I'he cores 2 all have substantially the same natural period of mechanical vibration. When stimulated magnetically by the elds of their respective coils 22, the cores 2 become slightly mechanically deformed. or distorted by magnetostriction. The resulting increment of deformation may he a lengthening, or a shortening, or some other distortion, depending on the material and on the polarity of the increment of the magnetic eld. Conversely, when the cores 2 are mechanically deformed or distorted, they will react or respond magnetically by magnetostriction with an increment of magnetization depending upon the nature of the preexisting magnetic eld and the mechanical deformation. The mechanical deformation is produced by exciting reversibl-einternal stresses in the core and the core readily recovers upon the Withdrawal of the deforming forces. i

The cores 2 may be in the form oftubes, or rods, or they may be otherwise constructed, as

explained in the said Letters Patent. As is also described in the said Letters Patent,- they are'. preferably of nickel, nickel-steel, nickel-copper, nickel-cobalt, chrome-nickel, chrome steel, or'of any other metal element or alloy characterized by 5.

comparatively large magnetostrictive effects and comparatively low vibrational decrement. By properchoice of length and other dimensions, the apparatus may be made applicable to systems of high or low frequency within a range 10 that may extend from a hundred cycles to hundreds of thousands of cycles. The system nds particular value at superaudible frequencies, the period of the said vibration and the consequent sound wavelength transmitted or received being 15 small enough so that the system shall be directively discriminating as to the sound. The diaphragm 58 is thus a directive diaphragm. The cores are preferably free from contact with the coils, so, as to reduce friction, which would pre- 20 vent free vibration.

The present invention provides a novel, mechanical, vibratory system, comprising the magnetostrictive cores-2 and a diaphragm 58, for use as a sonic oscillator in the production and recep- 25 tion of sounds of any desired frequency, particv ularly high frequencies, for sonorously communieating through air, Water, or other dense media I in which the diaphragm is positioned. The cores 2 are shown attached at their ends to one or 30.

more diaphragms 58 at separated, spaced posi. tions along a circle, but they may be positioned over substantially the whole extent of the diaphragm 58. In either case, the cores may add to the elastic forces acting on the diaphragm 58 35 andvcontribute to the period of vibration of the mechanical system constituted of the diaphragm and the cores. The cores 2 may serve also, parti ly or wholly, as elastic supports for the diaphragm 58, in the event that the diaphragm 58 is not 40 otherwise supported. The distances between the said spaced positions of the cores 2 should be small relatively to the wavelength of sound in the sound-conveying medium, in order that the vibrator shall be directively discriminating as 45 to the sound.l The diaphragm 58 constitutes a wall that is actuated by, or that actuates, the cores 2*, and that may. be positioned, for propagating elastic vibrations, in sonorous relation with a' sound-conveying medium, such as 50 air, or the water of the ocean, and constitutes a sound-radiating face for transmission'purposes, and a sound-receiving face for reception. The cores 2 effectively cooperatev with the diaphragm 58, through their magnetostrictive expansion and contraction, to i interchange energy with the sound-conveying medium. lOne of the faces 58 may be a rigid supporting plate, if desired, the other face 58 only. serving as a transmitting or receiving diaphragm. The magnetostrictive vibrator may be orientable as a unit, so as to cause the diaphragm 58 to assume any desired direction, or it may` be xed.

The coils 22 may be connected together, either in parallel or in series, as desired. The fields of adjacent coils 22 may be reversed, so that the lines of force may go to the right through one set of cores 2, and to the left through the alternately placed set of cores 2. Conductors l2 and I4 connect the cores 2 in series with a source of alternating electromotive force, such as an alternating-current generator I6, for passing an actuating periodic current through the coils 22. Other, more complicated, sources of alternating current are illustrated in' other gures of the above-entitled Letters Patent. A local battery I8, in series with the source I6 and the wind` ings 22, applies a steady magnetizing eld to the cores 2, over which the alternating eld produced by the generator I6 is superposed, so as to polarize the cores 2. The alternating ileld is preferably smaller than the steady eld, in order that the combined elds may not, at any time, fall to zero. The battery may be dispensed with, and the cores may be magnetized electromagnetically by a local source, or they may be permanently magnetized, instead, or the battery and permanently magnetized cores mayl be employed together. The magnetizing current may be passed through auxiliary coils, if desired.

If the current or voltage in the coils 22 is alternating, the electromagnetic field created thereby will also be alternating. The cores 2 will, therefore, increase and decrease in length (let us say) many .times a second, every variation in the current producing its stimulative eiect on the cores 2, and every deformation of the cores producing their reaction response upon the current. The'cores 2 will, in consequence, vibrate mechanically by magnetostriction, contracting and expanding lengthwise to and from nodal points in an lntermediately disposed, nodal plane. In an intermediate plane, parallel to and between the diaphragms 58, the cores 2 execute no appreciable movement; the two diaphragms may, however, move in opposite directions to and from each other. As the cores 2 are spaced from each other, they are free to expand and contract sidewise at their nodal planes, in a direction perpendicular to the before-mentioned, lengthwise vibration of the cores 2. The cores thus vibrate freely, with a period of vibration equal' to the period of the alternating electromotive force. Ordinarily, these vibrations will be quite small. When the alternating frequency is close to, or substantially the same as, the natural frequency of mechanical vibration of the system 2, however, the amplitude ofvibration of the cores, though still small, becomes relatively quite large. The cores 2 will then react magnetostrictively on the coils to render their consumption of power critical as to frequency for frequencies near the resonant frequency of the system. The vibrations of the diaphragm 58 will be correspondingly great. By proper choice of length and other dimensions, as before stated, the cores 2 may be proportioned effectively to transmit vibrational stresses lengthwise of the cores 2 to and from the dianhragms 58. Of course, there will usually be more than one specific frequency of magnetization at which the system will thus resonate; for in addition to a natural fundamental frequency of mechanical vibration, the system has also predetermined, natural frequencies of mechanical vi- 5 bration determined by the operation of the cores in. harmonic modes, as is explained more at length in the said Letters Patent, and it will be sufiicient here to remember that the operation described herein is equally applicable to the 10 fundamentals and their overtones.

As each core 2 is of relatively small, crosssectional area, the total aggregate of cross-sectional areas of the metal of the magnetostrictive cores 2 is but a small fraction of the whole 15 extent of the area of the diaphragm 58 over which the cores are disposed, as illustrated, ow- .ing to the spaced points at which the cores 2 are affixed to the diaphragm 58. Asl the cores 2 are of such small, cross-sectional areas, it is rela- 20 tively easy to compress and expand them, as a unit. The forces exerted by the cores 2 on the diaphragm 58 are, therefore, 'small compared to what they would have been had the cores 2 been packed closely together. A relatively high am- 2'5 plitude of vibration of the diaphragm 58 is thus permitted, together with good matching of the mechanical constants of the Vibratory unit Awith the mechanical constantsv of. the water. It is not necessary to pack the driving cores 2 continu- 30- ously and closely together, because ample power is obtainable, notwithstanding that the cores 2 are spaced. 'Ihe impressed voltage may be divided between the cores 2, particularly if their windings 22 are connected in series, though this 35' is also possible when the coils 22 are connected in parallel. As the vibration amplitude of a magnetostrictive core is limited only by the magnetic properties of the magnetostrictive material, furthermore, it is possible, by proper me- 40 chanical design, to transmit relatively tremendous electrical power to the diaphragm 58.

y The mechanical system is tuned to the desired frequency, inthe medium in which it is to be used. To get the maximum amplitude of the 45 previously designed vibrator, the electrical characteristics of the circuit will also be properly tuned, so as to have a substantially zero reactance for the natural period of mechanical vibration of the vibrator'by suitably tuning the 501 generator i6. By thus tuning the mechanical and the electrical systems to the same period into resonance witheach other, the current or voltage of lthe transmitter or the receiver becomes enor- -mously increased, so as resonantly to enhance, 55`

very greatly, the interconversion of sound and electric energy through the diaphragm 58, resulting from the magnetostrictive interaction between the diaphragm and the cores 2; suchinteraction resulting in actuation of the diae0 phragm 58 by the vibration of the cores 2, and the cores 2 being vibrated in response to the actuation of the diaphragm. The diaphragm 58 and its cores 2 may be so designed as to elasticity, length and other dimensions, and associated 65 mass, as to have, as a unit,v a natural period of mechanical vibration resonant to the frequency of the periodic current in the coils 22. The vibrator com'prising the diaphragm 58 and its cores 70 2 is actuable as such unit. A yielding, cylindrical band lforms, with the diaphragms 58, a chamber in which the coils 22 are contained, which chamber is then sealed against the entry 0f Water when submerged. The chamber forms 75 a rotatable, or orientable, submerged housing, or it may be xed.

The novel vibratory system of the presentinvention is thus constituted of a plurality of magnetostrictive bodies 2 separately dimensioned and tuned, in conjunction with the diaphragm 58, to the frequency of thel energizingcoils 22, for resonantly cooperating synchronously with the diaphragm 58 through their resonant expansion and contraction in response to the action of the energizing coils 20, to interchange electric and sound energy with the sound-conveying medium. By their magnetostrictive expansion and constraction, under the action of currents in the coils 22,

the cores 2 will cooperate with the coils 22 to vibrate the diaphragm means to produce radiation of sound into the medium. By their expansion and contraction in response to the incidence of sound in the medium upon the diaphragm means, the cores 2 will cooperate with the coils 22 to generate electric voltages in the coils 22. A multipleunit of this character will produce greater power than a single unit of corresponding area, and, is freer from eddy-current and hysteresis losses, besides being more flexible, so. as more easily to conform elastically to the natural medium in which it is operating. 'I'he number of magnetostrictive elements, their distribution and their lengths are of magnitudes suitable to easy ad-v justment for a predetermined resonant system designed to operate at any given frequency, within a wide range as, for example, 10,000 or 40,000 cycles per second. The distribution of driving members permits the ready radiation and distribution of heat, and lends itself to the use v`of large amounts of power. With thirty seven magnetostrictive driving elements, more than a kilowatt of power can be supplied to the system at l 30,000 cycles per second; and, by a 'larger number of elements, proportionally larger power may be used. The multiple-driven diaphragm is elastically supported at properly spaced, relatively small, distributed areas, capable of sharp and eiective tuning, with a large radiating face, and the system has low, mechanical, internal-power losses, capable of high rigidity, or of a rigidity adaptable to the medium in4 which it is used, by the choice of areas and distribution of driving elements. The system is also characterized by great durability, constancy, and high eiliciency. The magnetostrictive drive produces an elasticity and rigidity determined in large part by the driving rods or tubes themselves. A distribution of these members over the face of the diaphragm supplies rigidity to it at a multitude of points and insures a more uniform elasticity for the whole radiating diaphragm.

A sending-and-receiving system is illustrated in Fig. 3, using sound as the agency of communication, the transmitting and the receiving systems both having space-current oscillators. The transmitting system is designed for low decrement, and comprises a vacuum tube 1I, the output cir-1 cuit of which, between the filament or cathode 28 and the plate or anode 28, is provided with a coil 'I8 that is coupled to a coil 18. The grid is shown at 32. The coil 18 is connected in circuit with a tuning condenser 92 and the energizing coils 22 of a suitably oriented', magnetostrictive vibrator like that illustrated in Figs. 1 and 2. The coils 22 are thus connected with the coil 18 in the output circuit of the' space-current device fil. The vibrator may be polarized by a. parallel feed consisting of a source 93 of direct or alternat'' ing potential, and containing a choke coil 84 for l 3 conning the yoscillatory current to the circuit l containing the energizing coils 22. The energy of the vacuum tube 'Il is thus magnetostrictively transmitted to the sound-radiating diaphragm 58.

At high frequencies, this diaphragm 58 of the -5' transmitting system directively Atransmits along a straight line to the diaphragm 58 .of -the receiving system. A l

The supersonic sound waves so directly radiated are received by a suitably oriented sound-receiving vibrator of a receiving system. The energizing coils 22 of the receiving vibrator are connected in circuit with a tuning condenser 88 and a coil 84, a choke coil 8l and a potential source 88 being provided similar to the elements 84 and 15 83. The diaphragm 58 of the receiving system is thus magnetostrictively associated with the coil 84 which is coupled to a coil 86 in the input circuit of a receiving. vacuum tube 88. The tube 88 may have an amplifier for amplifying the 20 energy of the unitary vibratorso as to enhance the received signals and reduce the electricaldecrement of the circuits, and `that is connectedI with a telephone 88 for detecting oscillatory electric currents in the system. Additional tuning 25 condensers 98 and |88 may be employed for tuning the output circuits of the tubes 14 and 88 f the transmitter and the receiver respectively. The generator and associated parts will, as before, be electrically tuned.

The term "sound", as used herein, includes not merely audible sound, but all vibrations of a similar nature, including superaudible vibrations. If the sound frequency employed is above the audible range, the heterodyne principle may be used to render the signal audible. 4Instead of the inductive coupling shown in Fig. 3, other methods of coupling used .in related artsmay be employed.' Y

.It will readily be understood, without further 40 description, that the coils 22 of a single vibrator like that shown in Figs. 1 and 2 may be connected either to a transmitting -or a receiving apparatus, as by means of suitable switching ar rangements and, indeed, that each such apparatus may, in itself, be used either as a sending or a receiving apparatus. Other modifications, too, will be obvious to persons skilled in the art, and'all such are considered to fall within the spirit and scope of the present invention, as de- 5o A.

ned in the appended claims. I What is claimed is: 1. Apparatus for magnetostrictively interchanging Velectromagnetic energy'and sound en erg'y having, incombination, a support, a me- 55 Ychanical vibratorysystem comprising a diaphragm and av plurality of cores of highly mag# netostrictive material afilxed to the support and the diaphragm at separated, spaced positions, the diaphragm being adapted to be positioned in relation to a sound-conveying medium for sonor-4 ously inter-communicating energy 'with the medium by means of its sonorous vibration, the diaphragm having 'a restricted area to which its sonorous `vibration is coniined, and coil means magnetostrictively cooperativel with the cores, the aggregate cross-sectional area of .the metal of the `cores being small relative to the said area of duce radiation oi' sound into the medium, and to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium upon the diaphragm, to generate electric voltages magnetostrictively in the said coil means.

'2. A sound transmitter having, in combination, a support, a mechanical vibratory system comprising a diaphragm and a plurality of cores of highly magnetostrictive material ainxed to the support and the diaphragm at separated, spaced positions, the diaphragm being adapted to be positioned in relation to a sound-conveying medium to produce radiation of sound into the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is connned, and coil means magnetostrictively cooperative with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to the said area of the diaphragm, but the cores being. proportioned effectively to transmit vibrational stresses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the action of currents in the coil means, to vibrate the diaphragm to produce radiation of sound into the medium.

3. A sound receiver having, in combination, a support, a mechanical vibratory system comprising a diaphragm and a plurality of cores of highly magnetostrictive material aixed to the support 'and the diaphragm-at separated, spaced positions, the diaphragm being adapted to be positioned in relation to a sound-conveying medium for receiving sound from the medium, the diaphragm having a restricted area to which its sonorous vibration is conned, and coil means magnetostrictively cooperative with the cores, the

aggregate cross-sectional area of the metal of the cores being small relative to the 'said area of the diaphragm, but the cores being proportioned eiectively to transmit vibrational stresses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium upon the diaphragm, to generate,electric voltages magnetostrictively in the said coil means.

4. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system comprising ',a diaphragm and a plurality of cores of highly magnetostrictive material amxed to the support and the diaphragm at separated, spaced positions, the diaphragm being adapted to be positioned in relation toa sound-conveying medium for sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is confined, the diaphragm and the cores having elastic and mass constants andv diaphragm -in order to enable the cores to co- 75.

operate with the coil means, by their magnet strictive expansion' and contraction under the action of currents in the coil means, 'to lvibrate the diaphragm to produce radiation of sound into the medium, or to cooperate with the coil means,

by their expansion and contraction in response 5 to the incidence of sound in, the medium upon l the diaphragm, to generate electric voltages magnetostrictively in the said coil means.

5. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination,.a support, a mechanical vibratory system having `a natural period of vibration and comprising a'diaphragm and a plurality of cores of highly magnetrostrictive material alxed to thesuppprt and the diaphragm at separated, spaced positions, the diaphragm being adapted to be Vpositioned in relation to a] sound-conveying medium for` sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having 20 a restricted area to which its sonorous vibration is coniined, the diaphragm and the cores having elastic and mass constantsand dimensions of values to cause the diaphragm and the cores both to contribute substantially to the said natural 2. period of vibration of 'the mechanical system,

and coil means magnetostrictively cooperative with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to the said area of the diaphragm, but the cores being proportioned effectively to transmit vibrational stresses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under 35 the action of currents inthe coil means, to vibrate the diaphragm to produce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium 4o upon the diaphragm, to generate electric voltages magnetostrictively in the said. coil means.

6. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a support, a me- 45 chanical vibratory system having a natural perod of vibration and comprising a diaphragm. and a plurality of cores of highly magnetostrictive material affixed to the support and the diaphragm at separated, spaced positions,A the dia- 50 phragm being adapted to be positioned in relation to a sound-conveying Vmedium for sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vi- 55 bration is confined, the diaphragm and the cores having elastic and mass constants and dimensions of values to cause the diaphragm and the cores both to contribute substantially to the said natural period of vibration of the mechanical 60 system, the vibrational constants of the cores .cooperating with the diaphragm forces at the respective 'points of attachment of the cores to the diaphragm in order to facilitate the cophasing of the parts of the'diaphragm, and coil means 05 magnetostrictively cooperative with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to the said area of 1 the diaphragm, but the cores being proportioned eiectively to transmit vibrational stresses lengthwise of the cores to and from the diaphragm lin order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction undeia the action of currents in the coil means, to vibrate the diaphragm to prothe diaphragm, to generate electric voltages magduce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium upon the diaphragm, to gen` erate electric voltages magnetostrictively in the said coil means.

'7. Apparatus for magnetostrictively inter,- changing electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system comprising a diaphragm and a plurality of cores of highly mag'- netostrictive material ainxed .to the support and the diaphragm at separated, spaced positions, the diaphragm being adapted to be positioned in relation to a sound-conveying medium for sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is confined, the diaphragm and the cores having elastic and mass constants and dimensions of values to cause the diaphragm and the cores both to contribute substantially to the vibration of the mechanical system, the cores having substantial equality as to vibration constants, and coil means magnetostrictively cooperative with the cores, the aggregate cross-sectional area of, the metal of the cores being small relative to the said area of the diaphragm, but the cores being proportioned effectively to transmit vibrational stresses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the action of currentsy in the coil means, to vibrate the diaphragm to produce radiation of -sound into the medium, or to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium upon the diaphragm, to generate electric voltages magnetostrictively in the said coil means.

8. Apparatus for magnetostrictively changing electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system comprising a dia phragm and a plurality of cores of highly magnetostrictive material aiiixed to the support and the diaphragm at separated, spaced positions, the diaphragm being adapted to be positioned in relation to a sound-conveying medium for sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is confined, the diaphragm and the cores having elastic and mass constants and dimensions of values to cause the diaphragm and the cores both to contribute substantially to the vibration of the mechanical system, the cores having substantial equality as to vibrationconstants and having a comparatively low vibrational decrement to facilitate their vibrations, and coil means magnetostrictively cooperative with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to 'the said area of the diaphragm, but the cores being proportioned effectively to transmit vibra# tional stresses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the action of currents in the coil means, to vibrate the diaphragm to produce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium uponA inter- -coil means.

netostrictively in the said coil means.

9. Apparatus for magnetostrictively interchanging' electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory Asystem comprising adiaphragm and a'plurality of rigid tubular cores of highly magnetostrictive material aixed to the support and the'diaphragm at separated, spaced positions, the vdiaphragm being adapted to be positionedin relation to a sound-conveying medium for sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is "confined, and a coil for, and magnetostrictively cooperative with, each tubular core, the aggregate cross-sectional areaof the metal of the cores being small relative to the said area of` the diaphragm, but the cores being proportioned eiectively to transmit vibrational stresses lengthwise of the coresl to electricvoltages magnetostrictively in therespective coils.

10. Apparatus for magnetostrictively` interchanging electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system comprising a dlaphragm and a plurality of cores of highly magnetostrictive material axed to the support and the diaphragm at separated, spaced positions, the diaphragm being adapted to be positioned in a body of water for sonorously intercommunicating energy with the water by means of its ,sonorousvibration, the diaphragm having a restricted area to which its sonorous vibration is confined, the diaphragm and the cores having elastic and mass constants and dimensions of values to cause the diaphragm and the cores both to contribute substantially to the vibration of the mechanical system, and coil means magnetostrictively vcooperative with the cores, the aggregate crosssectional area of the metal of the cores being small relative to the said area of the diaphragm, but the cores being proportioned eiectively to transmit vibrational sin'esses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the action ofcurrents in the coil means, to vibrate the diaphragm to produce radiation of sound into the water, or to cooperate with the coil means, byI their expansion and contraction in response `to the incidence of sound in the water upon the diaphragm, lto generate electric voltages magnetostrictively in the said 65 11. Apparatus Yfor magnetostrictively interchanging electromagnetic energy and sound -energy having, in combination, a support, a

mechanical. vibratory system comprising a diaphragm and a plurality of cores of highly mag- 70 intercommunicating energy Awith the medium by 75 means oi its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is conned, and coil means magneto,- strictively cooperative with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to the said area of the diaphragm, but the cores being proportioned effectively to transmit vibrationalstresse's lengthwise of the cores to and from the diaphragm in order to' enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the action of currents in the coil means, to vibrate the diaphragm to produce radiation of sound into the medium, or to cooperate With the coil means, ,by their expansion and contraction in response to the incidence of sound in' the medium upon the diaphragm, to generate electric voltages magnetostrictively in the said coil means, the cores being separately dimensioned and tuned to cooperate eiectively with the frequency of the, current in the coil means. v

12. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system having a natural period of vibration and comprising-a diaphragm and a plurality of cores of highly magnetostrictive material amxed to the support and the diaphragm at separated, spaced positions over substantially the whole extent of the diaphragm, the diaphragm being adapted to be positioned in relation to a sound-conveying medium for sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having a restricted area to' which its son ous vibration is coni-ined, the diaphragm and the cores having elastic and mass constants and dimensions of values to causethe diaphragm and the cores both to contribute substantially to the said g natural period of vibration of the mechanical system, the vibrational constants of the cores cooperating with the diaphragm forces at the respective points of attachment of the cores to the diaphragm in order to facilitate piston-wise, cophasing oi the parts of the diaphragm, and coil means magnetostrictively cooperative with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to the said area of the diaphragm, but the cores being proportioned effectively to transmit vibrational stresses lengthwise of the cores to and from the diaphragm4 in order to enable the cores to c ooperate with the coil means, by their magnetostrictive expansion and contraction under the action of currents in the coil means, to vibrate the diaphragm piston-wise to produce radiation of sound into'the medium, or to cooperate with the coil means, by their expansion and contrac-` tion in response to the incidence of sound in the medium upon the diaphragm to drive the diaphragm piston-wise, to generate electric voltages magnetostrictively in the said coil means.

13. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system having a natural period of vibration and comprising a diaphragm and a plurality of cores of highly magnetostrictive material aiiixed to the support and the diaphragm at separated, spaced positions along a substantially closed, curved-path, the diaphragm being adapted to be positioned in relation to a sound-conveying medium for sonorously intercommunicating energy with the medium by means of its sonorous cooperative with Vthe cores, the aggregate .cross-I Y I sectional area of the metal of the cores being small relative to the said area of the diaphragm, but the cores being proportioned effectively to transmit vibrational stresses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coilimeans, by their magnetostrictive expansion and contraction under the action of currents in the coil means, to vibrateV the diaphragm piston-wise to produce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contraction-in response'to the incidence of sound in the medium upon the dia-4 phragm to drive the diaphragm piston-wise, to generate electric voltages magnetostrictiv'ely in the said coil means.

14. 'Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system having a natural period of vibration and comprising a diaphragm and .a plurality of cores of highly magnetostrictive material aixed to the support and the diaphragm at separated, spaced positions, the diaphragm being adapted to be positioned in relation to a sound-conveying medium for sonorously intercommunicating energy. with the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is conned, the diaphragm and the cores having elastic and mass constants and dimensions of values to cause the diaphragm and the cores both to contribute substantially to the said natural period of vibration of the mechanical system, the vibrational constants of the cores cooperating with the diaphragm forces at the respectivepoints of attachment of the cores to the diaphragm in order to facilitate piston-wise cophasing of the parts of the diaphragm, and coil means magnetostrictively cooperative with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to the said area'oi the diaphragm, but the ,cores being proportioned eiectively to transmit vibrational stresses lengthwise of the cores to-and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the vaction of currents in the coil means, to vibrate the diaphragm piston-wise to produce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium upon the diaphragm to drive the diaphragm pisaiiixed to the support and the diaphragm at sep arated, spaced positions, the diaphragm being adapted to be positioned in relation to a soundconveying medium for sonorously intercommunieating energy with the medium by means of its sonorous vibration, the diaphragm being of area having linear dimensions large compared with the effective .wave lengths of the intercommunication and having a restricted area to which its sonorous vibration is connned, the diaphragm and and the cores having elastic and mass constants and dimensions of values to cause the diaphragm and the cores both to contribute substantially to the said natural period o1 vibration of the mechanical system, the vibrational constants of the cores cooperating with the diaphragm forces at the respective points of attachment of the cores to the diaphragm, in order to facilitate the cophasing of the parts of the diaphragm at the said eiective wave lengths, and coil means magnetostrictively cooperative 'with the cores, the aggre'- gate cross-sectional area of the metal oi the cores being small relative to the said area of the diaphragm, but the cores being proportioned eifectively to transmit vibrational stresses lengthfwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the action of currents in the coil means, to vibrate the diaphragm to produce radiation of sound of the said effective 'wave lengths into the medium, or to cooperate with the coil means by their expansion and contraction in response to the incidence of sound oi the said effective wave lengths'in the medium upon the diaphragm, to generate electric voltages mag-l netostrictively in the said coil means. 16. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a support, a mechanical vibratory system having a natural period of vibration and comprising a diaphragm and a plurality of cores of highly magnetostrictive material ai-Iixed to the support and the dia-y phragm at separated, spaced positions, the cores being adapted to contract and expand lengthwise to and from intermediately disposed nodal planes to produce a piston-wise movement of the diaphragm and being free to expand and contract sidewise at the said nodal planes, the diaphragm being adapted to be positioned in relation to a. sound-conveying medium for sonorously intercommunicating energy with the medium by means of its sonorous vibration, the diaphragm having a restricted area to which its sonorous vibration is confined, the diaphragm and the cores having elastic and mass constants. and dimensions of values to cause the diaphragm and the c'ores both to contribute substantially to the said natural period of vibration of the mechanical system, the vibrational constants of the cores cooperating with the diaphragm forces at the respective points of attachment of the cores to the diaphragm, in order to facilitate the pistonwise cophasing of the parts of the diaphragm. and coil means magnetostrictively cooperative4 with the cores, the aggregate cross-sectional area of the metal of the cores being small relative to the said area of the diaphragm, but the cores ,being proportioned eectively to transmit vibra-Y tional stresses lengthwise of the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansionandcontraction under the action of currents in the coil means, to vibrate the diaphragm piston-wise to produce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contrac- .tion inresponse to the incidence of sound in the medium uponv the diaphragm to drive the diaphragm having a restricted area to which its 20 sonorous vibration is conilned, and coll means magnetostriotively cooperative'l with the cores, the aggregate cross-sectional area of themetal' ot the cores being small. relative to the said areal of the diaphragm, v'but the coresbeing proportioned eflectively to transmit-vibrational stresses lengthwise oi' the cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the vaction oi currents in the coil means, tol vibrate the diaphragm to produce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in the medium upon the diaphragm, togenerate electric voltages magnetostrictively in the said coil means, .and means yieldingly connecting the support and the dia. phragm.

18. Apparatus for magnetostrictively inter- 40- changing electromagnetic energy and sound energy having, in combination, a support, a.v mechanical vibratory system comprising a diaphragm and a plurality of cores of highly mag-- netostrictive material affixed to the support and 5 cores being small relative to the said area of the v diaphragm, but the cores being proportioned effectively to transmit vibrational stresses lengthwise of theI cores to and from the diaphragm in order to enable the cores to cooperate with the coil means, by their magnetostrictive expansion and contraction under the action of currents in the coil means, to vibrate the diaphragm to produce radiation of sound into the medium, or to cooperate with the coil means, by their expansion and contraction in response to the incidence of sound in themedium upon the diaphragm, to generate electric voltages magnetostrictively in. the said coil means, and means yieldingly connecting the diaphragm with the support, the diaphragm and thel yielding connecting means constltuting a housing in wbiclrthe cores are dis--l posed.

. GEORGE W. PIERCE. 

